Float type liquid level switch

ABSTRACT

A tube containing mercury is connected to the pump by a flexible cable and is contained within a water pipe float casing and is held by an encircling band so that it can pivot to one side or the other depending upon the attitude of the float casing. The pivotal mounting of the tube within the casing gives a clean snap action to the switch and eliminates inconsistent contacting of the mercury with the contacts which leads to excessive arcing.

United States Patent [1 1 Paradis et a1.

[ FLOAT TYPE LIQUID LEVEL SWITCH [76] Inventors: Arthur George Paradis; Guy B.

Paradis, both of Box 96, Dunrea, Manitoba, Canada [22] Filed: May 4, 1973 [21] Appl. No.: 357,398

[30] Foreign Application Priority Data May 18, 1972 Canada 142635 [52] US. Cl 200/84 B [51] Int. Cl. H0lh 35/18 [58] Field of Search 73/308, 322.5; 200/84 B [56] References Cited UNITED STATES PATENTS 1,941,815 1/1934 Ringstrom 200/84 B 3,045,084 7/1962 Sperowitz 200/84 B 1 Feb. 4, 1975 3,393,283 7/1968 Lenning 200/84 B FOREIGN PATENTS OR APPLICATIONS 221,019 7/1957 Australia 200/84 B Primary Examiner-David Smith, Jr. Attorney, Agent, or Firm-Stanley G. Ade

[57] ABSTRACT A tube containing mercury is connected to the pump by a flexible cable and is contained within a water pipe float casing and is held by an encircling band so that it can pivot to one side or the other depending upon the attitude of the float casing. The pivotal mounting of the tube within the casing gives a clean snap action to the switch and eliminates inconsistent contacting of the mercury with the contacts which leads to excessive arcing.

1 Claim, 5 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to new and useful improvements in float controls for liquid level switches and the like. Such controls may include a float mounted on the end of an arm which in turn is pivotted to the lower end of a support assembly through which conductor wires pass to a pump for pumping out liquids in a sewage sump or the like.

Such switches contain a rigidly mounted tube having a pair of contacts in one end and being connected to the cable so that as the water or liquid rises, the float tilts upwardly thus enabling a quantity of mercury within the tube to envelop or bridge the contacts thus closing the circuit and starting the pump. As the water level lowers, the float lowers and the mercury finally runs towards the other end of the tube thus breaking the contact.

SUMMARY OF THE INVENTION The principal disadvantages of such assemblies is the fact that as the water lowers, the mercury just moves away from the contacts so that the motor stops. Under these circumstances the float does not descend any further as no further liquid is being pumped out. Due to the fact that the mercury just moves away from the contacts, the slightest increase in liquid level causes the mercury once again to move towards the contacts thus giving rapid intermittent stopping and starting of the motor and often causing excessive arcing which can and often does result in the float assembly exploding as mercury is a particularly poor arcing material.

The present invention overcomes these disadvantages by pivotting the tube within the-float so that the weight of the mercury moving away from one end pivots the tube at approximately 45 angle thus giving a clean snap action to the making or breaking action. As the liquid rises the action of the switch retards until the float has risen sufficiently to enable the tube to pivot the other way once again causing the clean make or break contact and giving the necessary delay between maximum and minimum water levels which is often desired in most installations.

The principal object and essence of the invention is therefore to provide a device of the character herewithin described which includes a mercury contact tube which pivots thus giving a clean snap action to the making and breaking action of the tube switch.

Another object of the invention is to provide a device of the character herewithin described which, in the preferred embodiment, includes an arcuately curved mercury holding tube. This not only gives greater control to the snap action, but enables the pivot to be so positioned that a relatively low profile is provided thus cutting down on'the height of the float shell.

Still another object of the invention is to provide a device of the character herewithin described in which the support is through the flexible cable weighted at one end to maintain it principally in the vertical position. A further advantage flowing from this is the fact that as the float rises lowers, the cable curves rather than flexing at one point thus eliminating any danger of the cable breaking after continuous use.

A still further object of the invention is to provide a device of the character herewithin described which is simple in construction, economical in manufacture and otherwise well suited to the purpose for which it is designed.

With the foregoing objects in view, and other such objects and advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, my invention consists essentially in the arrangement and construction of parts all as hereinafter more particularly described, reference being had to the accompanying drawings in which:

DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially schematic view showing the mounting of the float assembly upon the support cable and showing the upper and lower positions in phantom.

FIG. 2 is a cross sectional view of one embodiment showing the float and switch in the switched closed position.

FIG. 3 is a view similar to FIG. 2, but showing the device in the switched open position.

FIG. 4 is a cross sectional view of the preferred embodiment of the float assembly.

FIG. 5 is an end view showing the method of mounting the tube for pivotal action to the supports.

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION Proceeding therefore to describe the invention, reference should first be made to FIG; 1 in which the float assembly collectively designated 10 is secured to one end 11 of a flexible cable 12 which extends substantially vertically to the remote location ofa pump motor (not illustrated).

Means are provided to hold the cable 12 in a substantially vertical position at all times, said means taking the form of a weight 13 secured around the cable adjacent to but spaced from the end 11 as clearly shown. This maintains the vertical portion of the cable in position but lets the float assembly 10 move upwardly to the upper water level shown in phantom by reference character 14 or downwardly to the lower water level shown in phantom by the reference character 14A. The weight secured around the cable 12 allows the cable to curve in the flexing action as clearly shown in phantom thus relieving strain at one point as the float raises and lowers.

FIGS. 2 and 3 show details of the float assembly. It consists of a hollow plastic shell having an upper half 15 and a lower half 16, the upper half having a peripheral flange 17 within which is seated the upper edge of the lower shell 16. These two halves are sealed together by any conventional adhesive means.

A cylindrical hollow stem 18 is formed integrally with and extends outside of the lower shell and this stem is screw threaded externally to receive a clamping nut 19. An 0 ring 20 engages between the nut and the screw threaded portion of the portion 18 and the end 12 of the cable extends through the nut and the portion 18 into the interior of the shell 10. By tightening the nut upon the screw threaded portion of the stem 18, the cable is held and sealed with relation to the float assembly l0.

Situated within the float assembly 10 is the switch mechanism collectively designated 21. It includes a cylindrical glass. or plastic tube 22 having a pair of contacts 23 within one end thereof connected by fine 3 flexible wires or conduits 24, to the end 11 of the cable 12.

A quantity of mercury 25 is provided within the tube sufficient to bridge the contacts 23 when the tube is in the position shown in FIG. 2.

A band 26 encircles the tube 22 intermediate the ends thereof and is mounted upon a pivot rod 27 spanning the spaced and parallel upright supports 28 which are secured to the base portion 29 of the lower shell 16 thus providing pivotal action to the tube as clearly illustrated. A strip of rubber or similar material 30 is secured between the supports 28 and acts as a shock absorber to receive the ends of the tube 22 as it pivots from one position to the other as clearly illustrated in FIGS. 2 and 3.

It will be noted that the tube 22 is cylindrical and substantially straight whereas in the preferred embodiment in FIG. 4 this tube is arcuately curved and has been identified by the reference character 22A. In this embodiment the ends 31 are lower than the central portion 32 when the tube is in the substantially horizontal position shown in FIG. 4. It is mounted in a similar manner to that hereinbefore described but because of the arcuate curvature, the pivot 27 gives a lower profile to the assembly thus allowing a relatively low profile shell to be utilized.

In operation, as the liquid level rises, the float pivots upwardly until it reaches the position shown in phantom in FIG. 1 and shown also in FIG. 2 at which time the mercury rolls from one end towards the contacts 23 thus enveloping same and closing the connection so that it acts as a switch. The weight of the mercury tilts the tube to the position shown in FIG. 2 with a snap action occurring so that there is no chance of arcing.

As the water is pumped out, the level lowers so that the tube moves toward the lowermost position indicated by reference character 14A in FIG. 1 and shown in FIG. 3. At some point, the weight of the mercury moves it away from the contacts it passes over the central portion of the tube and over balances the tube with a snap action to pivot it to the switch open position shown in FIG. 3.

The embodiment of FIG. 4 operates in a similar manner but here because of the arcuate curvature of the tube, the pivotal action is retarded in both directions Since various modifications can be made in my invention as hereinabove described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit'and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only'and not in a limiting sense.

What I claim as my invention is:

1. In a liquid level float assembly which includes a supporting electrical conductor and means adjacent to but spaced from the lower end of said conductor to maintain said conductor relatively vertical; a sealed plastic shell, a screw threaded stem extending from one end of said shell, gland nut means screw threadably engageable around said conductor and said screw threaded stem tosealably secure said shell to the lower end of said conductor with said lower end entering said shell, means controlled by the attitude of said shell to make and break electrical connections within said lower end of said cable, said last means including a tube capable of adopting a switched closed attitude and a switched open attitude, switch contacts in one end of said tube being operatively connected to said lower end of said cable a quantity of mercury within said tube sufficient to envelop said switch contacts when said tube is in the switched closed attitude and means pivotally mounting said tube intermediate the ends thereof whereby said tube can pivot around a transverse axis thereof to said switched closed and to said switched open position, said means pivotally mounting tube'including a pair of upwardly extending spaced and parallel supports secured to the base of said shell, a support clip surrounding said tube centrally thereof, means to pivot said support clip to said supports for tilting action, and shock absorber means on said base to receive the ends of said tube when same tilts from one position to the other and vice versa. 

1. In a liquid level float assembly which includes a supporting electrical conductor and means adjacent to but spaced from the lower end of said conductor to maintain said conductor relatively vertical; a sealed plastic shell, a screw threaded stem extending from one end of said shell, gland nut means screw threadably engageable around said conductor and said screw threaded stem to sealably secure said shell to the lower end of said conductor with said lower end entering said shell, means controlled by the attitude of said shell to make and break electrical connections within said lower end of said cable, said last means including a tube capable of adopting a switched closed attitude and a switched open attitude, switch contacts in one end of said tube being operatively connected to said lower end of said cable a quantity of mercury within said tube sufficient to envelop said switch contacts when said tube is in the switched closed attitude and means pivotally mounting said tube intermediate the ends thereof whereby said tube can pivot around a transverse axis thereof to said switched closed and to said switched open position, said means pivotally mounting tube including a pair of upwardly extending spaced and parallel supports secured to the base of said shell, a support clip surrounding said tube centrally thereof, means to pivot said support clip to said supports for tilting action, and shock absorber means on said base to receive the ends of said tube when same tilts from one position to the other and vice versa. 